Steerable catheter

ABSTRACT

A catheter, which is adapted to be inserted into a body lumen, comprises a symmetrical cylindrical control handle, an elongate tubular catheter body, and a flexible catheter tip having a lumen offset from the axis of the catheter tip. The control handle comprises a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is fixedly attached to the distal end of the piston. A puller wire is attached to the housing and extends through the piston, through and coaxial with the catheter body and into the offset lumen of the catheter tip where it is attached to the wall of the catheter tip. Lengthwise movement of the piston relative to the housing results in deflection of the catheter tip.

FIELD OF THE INVENTION

This invention relates to steerable catheters for use in a body lumen,and more specifically to a rotatable electrode catheter having asteerable tip.

BACKGROUND OF THE INVENTION

Catheters have been in common use in medical practice for many years.They are used to probe locations inside a body lumen which are otherwiseunreachable without surgery. A catheter is first inserted into a majorvein or artery, or other body lumen which is near the body surface. Thecatheter is then guided to the area of concern by further inserting itinto the body lumen. As medical knowledge increases, catheterizationshave become more complicated and more exacting. In many situations theability to control the exact position and orientation of the cathetertip largely determines how useful the catheter is.

The body of a catheter is long and tubular. The problem of control oversuch a device has resulted in catheters which are generally rigid andpreformed into specific shapes. This is exemplified by U. S. Pat. No.3,485,234 to Stevens, which describes a method for making a catheter isany desired shape. However, given the complexity of body lumens, eachpreformed catheter can only reach certain areas. Thus, for manyexaminations, multiple catheters are needed, either inserted together oreach one in turn. In either case, this greatly adds to the complexity ofthe procedure and create additional risk for the patient.

Flexible catheters having steerable tips are also known. Such cathetershave control handles at their proximal ends controlling the tips. U. S.Pat. No. 4,586,923 to Gould describes many of these. The mechanismsdescribed involve control handles which are asymmetrical. This resultsin the control handle being less effective when it is rotated, as thecontrols are no longer in a convenient position to use. Control of thecatheter is therefore limited, as the user is not free to rotate thedevice without losing some control over it.

A catheter often has probes of some kind, e.g., electrodes, on its tipin order to deliver stimuli and/or take measurements within he bodylumen. In such a catheter, the probe is electrically connected to aninstrument capable of generating the stimuli or recording and/orinterpreting signals received by the probes. The connection to thisadditional instrument generally involves the use of multiple wires whichplug into separate sockets, as shown in U. S. Pat. No. 4,603,705 toSpeicher, or the use of a single multiple pin plug which fits into acorresponding multiple pin socket. In either case, if the catheter isrotated, the connections must be unplugged and reset, since theyotherwise restrict the movement of the catheter. This problem furtherincreases the risks mentioned above in regards to multiple catheters.Each catheter has its own connections, all of which will need to bereset as the catheters are manipulated. The additional loss of data flowand increased procedure length further increase the risk to the patient.

SUMMARY OF INVENTION

This invention therefore provides a steerable catheter having asymmetrical control handle which can be rotated freely while in use. Thecatheter comprises an elongated catheter body having a first lumen whichextends through the catheter body. The catheter tip is fixedly attachedto the distal end of the catheter body. The catheter tip comprises alumen which is offset from the axis of the catheter tip.

A control handle is attached to the proximal end of the catheter body.The control handle comprises a generally symmetrical housing having apiston chamber at its distal end. A piston having a longitudinal andpreferably axial bore is mounted within the chamber and is manuallymovable lengthwise within the chamber. The proximal end of the catheterbody is fixedly attached to the distal end of the piston.

An elongated puller wire is fixedly attached to the control handlehousing at a location proximal to the piston and extends through thebore of the piston, through and preferably coaxial with the lumen of thecatheter body and into the off-axis lumen of the catheter tip. Thedistal end of the puller wire is fixedly attached to the wall of thecatheter tip. In such an arrangement, movement of the piston relative tothe housing causes movement of the puller wire relative to the catheterbody and the catheter tip, resulting in deflection of the catheter tip.

In a preferred embodiment of the invention, the catheter tip comprisesone or more electrodes. Lead wires extend from the control handlethrough the lumen of the catheter body, preferably through a lumen inthe catheter tip, and preferably a second off-axis lumen, and are thereelectrically connected to the electrodes.

In the control handle, the electrode leads extend through the bore ofthe piston and through the housing of the control handle to anelectrical connector for connecting the leads to a electrical stimulatorand/or recorder. In such an embodiment, it is preferred that theconnector is a rotary connector to afford rotatable movement to thecontrol handle and catheter without breaking electrical contact with thestimulator and/or recorder.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a longitudinal cross-sectional external view of a preferredelectrode catheter constructed in accordance with the present invention;

FIG. 2 is an enlarged view of the junction of the catheter body and thecatheter tip;

FIG. 3 is an enlarged cross-sectional view of the catheter tip showingthe attachment of the puller wire; and

FIG. 4 is an enlarged longitudinal cross-sectional view of the controlhandle.

DETAILED DESCRIPTION

FIG. 1 illustrates a preferred electrode catheter constructed inaccordance with the present invention. The electrode catheter 10comprises an elongated catheter body 11 having proximal and distal ends,a catheter tip 12 at the distal end of the catheter body 11, and acontrol handle 13 at the proximal end of the catheter body 11.

The catheter body 11 comprises an elongated tubular construction sectionhaving a single lumen 15. The catheter body 11 is flexible, i.e.,bendable, but substantially non-compressible along its length. Thecatheter body 11 may be of any suitable construction and made of anysuitable material. A presently preferred construction comprises a nylontube surrounded by braided stainless steel with a polyurethane coating.

The length and diameter of the catheter body 11 are not critical and mayvary according to the application. For the electrode catheter shown inthe accompanying drawing, a length of about 48 inches, an outer diameterof about 0.09 inch, and an inner diameter, i.e. lumen diameter, of about0.03 to about 0.04 inches is presently preferred.

The catheter tip 12 comprises a short section of flexible tubing 16having a pair of nonoverlapping, e.g., side-by-side first and secondlumens 17 and 18 which are off-axis, i.e., are not coaxial with cathetertip 12. The tubing 16, may be made of any suitable materials, and ispreferably more flexible than the catheter body. A presently preferredmaterial for the catheter tip is polyurethane having a D55 hardness.

The diameter of the catheter tip 12 is not critical, but is preferablyabout the same as, or slightly smaller, than the diameter of thecatheter body 11. The length of the catheter tip 12 is likewise notcritical. The embodiment shown, the length of the catheter tip 12 isabout two inches.

Along the length of the flexible tubing 16, there are a plurality ofelectrodes 21. The electrodes 21 are in the form of metal rings, theouter diameter of the electrodes 21 being about the same as the outerdiameter of the flexible tubing 16 so that the electrodes 21 form asmooth, continuous surface with the outer surface of the flexible tubing16. A rounded end electrode 22 is positioned at the distal end of thecatheter tip 12.

A preferred means for attaching the catheter tip 12 to the catheter body11 is shown in FIG. 2. The proximal end of the catheter tip 12 comprisesan outer circumferential notch 26 and the distal end of the catheterbody 11 comprises an inner circumferential notch 27. The notches 26 and27 are sized to allow the notched proximal end of the catheter tip 12 tobe snugly inserted into the notched distal end of the catheter body 11.The catheter tip 12 is then fixedly attached to the distal end of thecatheter body 11 by glue or the like. As shown, the lumen 15 of thecatheter body 11 is in communication with both off-axis lumens 17 and 18of the catheter tip 12.

A puller wire 30, preferably made of stainless steel, extends from thecontrol handle 13 through the lumen 15 of the catheter body 11 and intothe first lumen 17 of the catheter tip 12. The puller wire 30 extendsinto the first lumen 17 of the catheter tip 12 to a position near thedistal end of the catheter tip 12 and is fixedly attached to the wall ofthe flexible tubing 16. The puller wire 30 is preferably surrounded by ateflon sheath 31 or the like for lubricity and to keep the puller wire30 generally coaxial with the catheter body 11. In the first lumen, thesheath 31 is swaged, i.e., thinned to smaller wall thickness toaccommodate the smaller first lumen 17 of the catheter tip 12.

A preferred means for attaching the puller wire 30 to the wall of thecatheter tip is shown in FIG. 3 and comprises a short piece of tubularstainless steel 32, e.g., hypodermic stock, which is fitted over thedistal end of the puller wire 30 and crimped to fixedly secure thepuller wire 30. The distal end of the tubular stainless steel 32 isfixedly attached, e.g., by welding, to a stainless steel crosspiece 33such as stainless steel ribbon or the like. The crosspiece 33 sitswithin a notch 34 in the wall of the flexible tubing 16 which extendsinto the first lumen 17. This provides an opening through the wall ofthe flexible tubing 16 into the first lumen 17. The stainless steelcrosspiece 34 is larger than the opening and, therefore, cannot bepulled through the opening. The portion of the notch 34 not filled bythe crosspiece 33 is filled with glue or the like, preferably apolyurethane glue harder than the material of the flexible tubing 16.Rough edges, if any, of the crosspiece 34 are polished to provide asmooth, continuous surface with the outer surface of the flexible tubing16.

Electrode lead wires 36 extend from the control handle 13 through thelumen 15 of the catheter body 11 and into the second lumen 18 of thecatheter tip 12. The lead wires 36 are attached to the electrodes 21 and22 by any conventional technique.

With reference to FIG. 4, the control handle 13 comprises a generallycylindrical housing 40 having open chambers at each end. A pistonchamber 41 is at the distal end of the housing 40, and a connectorchamber 42 is at the proximal end of the housing 40. There is an axialpassageway 43 and an offset passageway 44 leading from the pistonchamber 41 to the connector chamber 42. The housing is generallysymmetrical about its longitudinal axis. This allows the control handleto be freely rotated without altering convenience or quality of control.

A cylindrical piston 46 is slidably disposed within and generallycoaxial with the piston chamber 41. The piston 46 comprises acircumferential O-ring notch 47 which carries an O-ring 48 to provide asnug, watertight fit between the piston 46 and the wall of the pistonchamber 41.

The piston 46 further comprises a slot 49 extending along a portion ofits length proximal to the O-ring notch 47. When the piston 46 isdisposed within the piston chamber 41, a pin 51, e.g. a set screw,extends from the wall of the housing 40 into the slot 49. The piston 46can slide distally until the pin 51 engages the proximal end of the slot49 and proximally until the pin 51 engages the distal end of the slot49. Thus, the pin 51 and slot 49 limit lengthwise movement of the piston46 within the piston chamber 41 and prevent the piston 46 from beingpushed out of the piston chamber 41.

The piston 46 has an axial bore 52 along its length. The diameter of theaxial bore 52 is about the same as the outer diameter of the catheterbody 11. The catheter body extends into the axial bore 52 and is fixedlyattached, e.g. by glue, to the piston 46.

The distal end of the piston 46 extends beyond the distal end of thehousing 40, in order that it may be manually controlled by the user. Anannular thumbrest 54 is attached to the distal end of the piston 46 tofacilitate lengthwise movement of the piston 46.

The puller wire 30 extends through the axial bore 52 of the piston 46and is fixedly attached to the housing 40 by means of an anchor 56. Theanchor 56 extends into a transverse hole in the portion of the housing40 between the connector chamber 42 and piston chamber 41. The anchor 56blocks the axial passageway 43, but not the offset passageway 44. Theanchor 56 is rotatable within the hole, but fits snugly so that it doesnot rotate freely.

The anchor 56 comprises a transversely extending hole 57 which can berotated into alignment with the axial passageway 43. To secure thepuller wire 30 to the anchor 56, the puller wire 30 is passed throughthe axial passageway 43 and transversely extending hole 57 in the anchor56 and the anchor 56 is rotated to wedge the puller wire 30 between theanchor 56 and the wall of the housing 40. Tension on the puller wire 30can be adjusted by rotation of the anchor 56.

In use, the catheter tip can be curved or bent to steer the tip into abranching lumen, e.g., a branching blood vessel, by gripping the controlhandle housing and moving the piston distally out of the piston chamberby pushing outwardly on the thumbrest. Because the catheter body isattached to the piston and the puller wire is attached to the housing,this action causes movement of the puller wire relative to the catheterbody and tip, effectively pulling the catheter tip proximally toward thecatheter handle. Because the puller wire is offset from the axis of thetip, the tip bends in the direction of the offset, as shown in FIG. 1,to accommodate the force exerted on it.

In use, catheters are often rotated slowly as the catheter is passedthrough a body lumen, e.g. artery. The rotation facilitates passagearound bends in the body lumen. The symmetrical design of the handleprovides the unique advantage of allowing the handle to be rotatedwithout affecting or altering the manner in which the handle is grippedand manipulated by the physician. Such a design thus facilitates thesmooth manipulation of the catheter.

Another unique advantage is provided by maintaining the puller wire incoaxial relation with the catheter body. Often a catheter is insertedinto a body lumen and is bent or curved because the body lumen curves orbends. In such a situation, a puller wire which is offset from the axisof the catheter body tends to predispose the catheter in a curved shapewherein the puller wire lies on the inside of the curve. Such a catheteracts like a preformed catheter, i.e. a catheter having a preformedshape, and resists rotation. This is because in such an arrangement, thelength of the puller wire is less than the on-axis length of thecatheter. This means that rotation of the catheter one-half turnrequires the puller wire to move to the outside of the curve. To dothis, however, the on-axis length of the catheter must be compressed orreduced relative to the length of the puller wire, Thus, before the tiprotates, the handle must be rotated sufficiently to build sufficienttorque to supply the energy required to compress the catheter body. Theresult is that rotation of the tip lags far behind rotation of thehandle which makes control of the tip difficult.

By maintaining the puller wire in coaxial relation with the catheterbody in accordance with the present invention, the length of the pullerwire and on-axis length of the catheter body are the same, whether thecatheter body extends around a curve or not. In this arrangement, lessenergy is required for rotation of the catheter tip. This allows the tipto be more responsive to rotation of the handle and therefore moreeasily controlled.

The electrode lead wires 36 extend from the catheter body 11 proximallythrough the axial bore 52 of the piston 46, the piston chamber 41, theoffset passageway 44 between the piston and connector chambers 41 and42, and into the connector chamber 42. A teflon sheath 59 surrounds andprotects the electrode lead wires 36 in the piston chamber 41, offsetpassageway 44 and connector chamber 42. Within the piston chamber 41, ormore preferably the connector chamber 42, the lead wires 36 and sheath59 are bowed or looped to provide slack as the catheter is manipulated.

In the connector chamber 42, the lead wires 36 are connected to a rotaryconnector 60. The rotary connector 60 comprises a cylindrical male plug61 extending proximally from the control handle housing 40 coaxiallywith the housing 40. The plug 61 is of conventional design and has aseries of electrical contacts or terminals 62 along its length, each ofwhich is electrically connected to a separate lead 62, and, therefore, aseparate lead wire 36, within the connector chamber 42. These terminalsoperate independently to allow separate electrical signals to betransmitted through the connector 60 simultaneously. The plug may beinserted directly with a stimulator/recorder or other electrical deviceor more preferably, connected to the female end to a floating extensioncable which in turn has a node plugged to its opposite end which can beplugged into the electrical device.

In the embodiment shown, the catheter tip 12 carries four electrodes andthe rotary has four terminals. It is understood that the number ofelectrodes and terminals may vary as required. Due to its symmetry, therotary connector 60 can continuously convey electrical signals while thecontrol handle 13 is rotated. This allows greater freedom of movement ofthe catheter and particularly the control handle without needing toreset the electrical connections and risk losing data.

An annular flange 64 secures the rotary connector 60 to the housing 40and seals the proximal end of the connector chamber 42. Preferably,there is a vent 66 leading from the connector chamber 42. The vent 66can be through the housing wall, flange 64 or through the plug 61 of therotary connector as shown.

The preceding description has presented with reference to a presentlypreferred embodiment of the invention shown in the drawings. Workersskilled in the art and technology to which this invention pertains willappreciate that alterations and changes in the described structures canbe practiced without meaningfully departing from the principal, spirit,and scope of this invention.

For example, it is apparent that the invention is applicable tocatheters other than electrode catheters. In such other embodiments,there may be no need for an electrical connector at the proximal end ofthe control handle. Such other catheters may be designed, for example,to deliver medications, or the like, to a particular location in a bodylumen or to take fluid samples from a particular location. In such anembodiment, a continuous lumen may extend through the housing, piston,catheter body, and catheter tip. Other catheters to which this inventionis applicable may include, for example, an optic fiber for viewing thelumen or for delivering laser irradiation to the lumen, e.g. to removeplaque in a blood vessel.

It is also apparent that, if the catheter is an electrode catheter, thenumber, size and location of the electrodes may vary. Moreover, therotary connector may, for convenience, include a cord extending betweenthe control handle housing and the male plug of the connector. Such anembodiment is preferred if it is desired that the handle not be adjacentthe stimulator and/or recorder.

The design for the catheter may vary in other respects. For example, thenumber of lumens in the catheter body and/or catheter tip may vary asdesired. It is preferred that the puller wire be coaxial with thecatheter body. To facilitate this, the electrode lead wires may bewrapped around the puller wire sheath rather than extending to one sideas shown in the drawing.

While it is preferred that the handle be symmetrical about itslongitudinal axis to enable easy manipulation of the handle while beingrotated, it is understood that nonsymmetrical variations may be used ifdesired. Likewise, it is understood that any suitable method forattaching the puller wire to the catheter tip and to the control handlehousing may be used.

Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and shown in the accompanyingdrawings, but rather should be read consistent with and as support tothe following claims which are to have their fullest and fair scope.

What is claimed is:
 1. A steerable catheter comprising:a flexibleelongated catheter body having proximal and distal ends and a firstlumen; a flexible catheter tip fixedly attached to the distal end of thecatheter body, said tip comprising a second lumen, the axis of thesecond lumen being offset from the axis of the tip; a control handle atthe proximal end of the catheter body, said control handle comprising:ahousing having proximal and distal ends and a piston chamber at itsdistal end; a piston having proximal and distal ends and a longitudinalbore therethrough mounted in the piston chamber of the housing andmoveable longitudinally within the piston chamber, wherein the proximalend of the catheter body is fixedly attached to the distal end of thepiston; and means proximal to the piston, for securing the proximal endof a puller wire to the housing; an elongated puller wire having aproximal end fixedly attached to the securing means at a locationproximal to the piston chamber, said puller wire extending through thebore of the piston, the first lumen of the catheter body and into thesecond lumen of the catheter tip, said puller wire further comprising adistal end fixedly attached to the catheter tip; and wherebylongitudinal movement of the piston relative to the housing results indeflection of the catheter tip.
 2. A catheter as claimed in claim 1wherein the puller wire is generally coaxial with the catheter body. 3.A catheter as claimed in claim 1 wherein the distal end of the pistonextends out of the distal end of the housing and comprises a thumbrestto facilitate manual movement of the piston relative to the housing. 4.A catheter as claimed in claim 1 wherein the piston comprises acircumferential notch along its length, and the control handle comprisesan O-ring positioned within the notch for forming a generallywater-tight seal between the piston and the housing.
 5. A catheter asclaimed in claim 1 wherein the piston comprises a slot along a portionof its length, and the control handle comprises a pin which extends fromthe housing into the slot.
 6. A catheter as claimed in claim 1 whereinthe housing comprises a transversely extending bore proximal to thepiston, and the securing means comprises an anchor positioned within thebore, said anchor having a hole through which the puller wire extends,and wherein the anchor is rotatable to thereby wedge and secure theproximal end of the puller wire between the anchor and the housing.
 7. Asteerable electrode catheter comprising:a flexible, elongated catheterbody having proximal and distal ends and a lumen; a flexible cathetertip fixedly attached to the distal end of the catheter body, said tipcomprising at least one electrode and at least one lumen having an axisoffset from the axis of the tip; a control handle at the proximal end ofthe catheter body, said control handle comprising:a housing havingproximal and distal ends and a piston chamber at its distal end and aconnector chamber at its proximal end; a rotary connector attached tothe proximal end of the housing, the rotary connector comprising: a maleplug having a terminal for electrical connection with each electrode;and a contact which extends into the connector chamber electricallyconnected to each terminal; a piston having proximal and distal ends anda longitudinal bore therethrough mounted in the piston chamber of thehousing and moveable longitudinally within the piston chamber, whereinthe proximal end of the catheter body is fixedly attached to the distalend of the piston; and means proximal to the piston, for securing theproximal end of a puller wire to the housing; an elongated puller wirehaving a proximal end secured to the securing means, said puller wireextending through the bore of the piston, through the first lumen of thecatheter body in generally coaxial relation to the catheter body andinto the offset lumen of the catheter tip, said puller wire furthercomprising a distal end fixedly attached to the catheter tip wherebylongitudinal movement of the piston relative to the housing results indeflection of the catheter tip; and an electrode lead associated witheach electrode, each electrode lead having a distal end attached to anelectrode and extending through the catheter tip, catheter body, andpiston and into the connector chamber of the housing wherein theelectrode lead is attached to a contact of the rotary connecter.
 8. Acatheter as claimed in claim 7 wherein the distal end of the pistonextends out of the distal end of the housing and comprises a thumbrestto facilitate manual movement of the piston relative to the housing. 9.A catheter as claimed in claim 7 wherein the piston comprises acircumferential notch along its length and the control handle comprisesan O-ring positioned within the notch for forming a generallywater-tight seal between the piston and the housing.
 10. A catheter asclaimed in claim 7 wherein the piston comprises a slot along a portionof its length and the control handle comprises a pin which extends fromthe housing into the slot.
 11. A catheter as claimed in claim 7 whereinthe housing comprises a transversely extending bore proximal to thepiston and the securing means comprises an anchor positioned within thebore, said anchor having a hole through which the puller wire extends,and wherein the anchor is rotatable to thereby wedge and secure theproximal end of the puller wire between the anchor and housing.
 12. Acatheter as claimed in claim 7 wherein the rotary connector comprises aflexible core between the contacts and the male plug. .Iadd.
 13. Asteerable catheter comprising:a flexible, elongated catheter body havingproximal and distal ends and a first lumen formed therein in coaxialrelation with the catheter body; a flexible catheter tip portion fixedlyattached to the distal end of the catheter body, said tip portion havingproximal and distal ends and a second lumen wherein the axis of thesecond lumen is offset from the axis of the tip portion; an elongatedpuller wire having a proximal end located at the proximal end of thecatheter body and a distal end at the catheter tip portion, the pullerwire being disposed in and extending through the first lumen in coaxialrelation with the catheter body and into the second lumen, the distalend of the puller wire being secured to the catheter tip portion,wherein the catheter further comprises means for supporting the pullerwire in the first lumen in coaxial relation with the catheter body,whereby longitudinal movement of the puller wire results in deflectionof the catheter tip portion; and means located at the proximal end ofthe catheter body for controlling longitudinal movement of the pullerwire. .Iaddend. .Iadd.
 14. A catheter as claimed in claim 13, whereinthe means for supporting the puller wire in the first lumen such thatthe puller wire is coaxial with the catheter body comprises a sheatharound the puller wire, said sheath further providing lubricity for thepuller wire in the first lumen. .Iaddend.